Entrapment of immune complexes in the choroid plexus has been demonstrated in chronic viral infections, experimental and spontaneous immune complex diseases. This proposal is designed to; 1) study the pathology of the choroid plexus in acute and chronic serum sickness of rabbits, 2) demonstrate permeability changes of the choroid plexus in acute and chronic immune complex disease in rabbits and (NZB x W) F1 mice, 3) determine the incidence of immunoglobulin deposits in human postmortem choroid plexus. The methods are immunofluorescence and electron microscopy. The results are expected to contribute to the understanding of neuropsychiatric disorders known to occur in human immune complex diseases such as systemic lupus erythematous.